Dye/metal ion-based chemosensing ensemble towards l-histidine and l-lysine determination in water via different optical responses.

In this study, a novel simple type of label-free, ultra-sensitive, and highly selective UV-Vis absorption and naked-eye detection of histidine (His) and lysine (Lys) using a dye/metal ion ensemble is developed. The outcoming high sensitivity and selectivity for histidine and lysine were attained by changing the metal ions. The indicator is released due to its displacement from the murexide (Mure)/Cu2+ complex by histidine and the change in absorbance may be due to the further complexation of lysine with the additional coordination sites present in the zinc atom of Mure/Zn2+ complex. The label-free chemosensor provided sensitive and selective detection of l-histidine and l-lysine with detection limits of 9.1 and 9.4 nmol L-1, respectively. The protocol especially offers high selectivity for the determination of His and Lys among amino acids found in human urine samples. Furthermore, INHIBIT and NAND molecular logic gates were obtained using chemical inputs and UV-Vis absorbance signal output.